U.S. patent number 5,575,394 [Application Number 08/276,096] was granted by the patent office on 1996-11-19 for wafer shipper and package.
This patent grant is currently assigned to Fluoroware, Inc.. Invention is credited to David L. Nyseth.
United States Patent |
5,575,394 |
Nyseth |
November 19, 1996 |
Wafer shipper and package
Abstract
A plastic container for storing and shipping semiconductor
wafers comprising a wafer carrier of substantially rigid and
transparent material supporting the wafers and maintaining the
wafers in spaced relation to each other, top and bottom covers for
the wafer carrier formed of stiff but resiliently flexibly
yieldable material, the wafer carrier having upper and lower
enlarged rim portions extending around the peripheries of the top
and bottom of the wafer carrier and being embraced by enlarged
peripherally extending rim portions of the top and bottom covers,
the top and bottom covers having partially cylindrical panels with
elongate beads or ridges formed thereon to engage and maintain the
edges of the wafers spaced from the partially cylindrical surfaces,
offset tabs on the wafer carrier and top and bottom covers
facilitating of flexibly lifting small portions of the covers off
the wafer carriers and then progressively disengaging the covers
from the wafer carriers; a package comprising a multiplicity of
cover trays with compartments receiving the shipping containers
therein, the cover trays supporting the containers at the tab
portions on the wafer carriers and the cover trays also bearing
downwardly on the side edge portions of the cover to maintain the
covers in closed condition on the wafer carrier.
Inventors: |
Nyseth; David L. (Plymouth,
MN) |
Assignee: |
Fluoroware, Inc. (Chaska,
MN)
|
Family
ID: |
23055147 |
Appl.
No.: |
08/276,096 |
Filed: |
July 15, 1994 |
Current U.S.
Class: |
206/710; 206/711;
206/723; 206/454 |
Current CPC
Class: |
H01L
21/67369 (20130101); H01L 21/67386 (20130101); H01L
21/67373 (20130101); H01L 21/67383 (20130101); Y10S
206/832 (20130101) |
Current International
Class: |
H01L
21/67 (20060101); H01L 21/673 (20060101); B65D
073/02 () |
Field of
Search: |
;206/334,454,707,710,711,722,723 ;220/4.21,306,212.5,771 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sewell; Paul T.
Assistant Examiner: Patterson; Marie Denise
Attorney, Agent or Firm: Palmatier, Sjoquist & Helget,
PA
Claims
We claim:
1. A plastic container for storing and shipping semiconductor
wafers and interfacing with processing machines in indexing
relation comprising a wafer carrier comprising sidewalls with wafer
supporting offset portions and wafer separating ribs, the carrier
also comprising first and second end walls interconnecting the
sidewalls, the sidewalls and end walls comprising upper edge
portions defining a top opening of the carrier facilitating loading
and unloading of wafers, the sidewalls and end walls also defining
lower edge portions defining a bottom opening of the carrier
providing access to the wafers in the carrier, said upper edge
portions comprising enlarged upper rim portions, said lower edge
portions of the carrier comprise enlarged lower rim portions, the
wafer carrier comprises a periphery adjacent the lower edge
portions thereof, the lower edge portions and the lower rim
portions of the carrier extend entirely around the periphery of the
wafer carrier,
a bottom cover removably traversing the bottom opening of the wafer
carrier and lying against said lower edge portions to close the
bottom opening, and the bottom cover comprises a periphery and also
comprises enlarged bottom cover rim portions extending around the
entire periphery of the bottom cover and engaging and embracing the
lower rim portions of the wafer carrier in a snap fit and removably
retaining the bottom cover on the carrier, said lower edge portions
of the sidewalls comprising indexing notches opening through said
lower edge portions, the lower rim portions of the carrier and the
bottom cover rim portions continuing along and bypassing said
indexing notches,
a bottom cover removably traversing the bottom opening of the wafer
carrier and lying against said lower edge portions to close the
bottom opening, and the bottom cover comprises a periphery and also
comprises enlarged bottom cover rim portions extending around the
entire periphery of the bottom cover and engaging and embracing the
lower rim portions of the wafer carrier in a snap fit and removably
retaining the bottom cover on the wafer carrier,
and a top cover removably traversing the top opening of the wafer
carrier and lying against said upper edge portion of the carrier to
close the top opening and retain the wafers, the top cover
comprising enlarged top cover rim portions engaging and embracing
upper rim portions of the wafer carrier in a snap fit and removably
retaining the top cover on the wafer carrier.
2. A plastic container according to claim 1 wherein the lower rim
portion of the wafer carrier and the bottom cover rim portion of
the wafer carrier have surface portions lying flush against each
other and engaging each other and establishing a hermetically
sealing relation there between.
3. A plastic container according to claim 1 wherein the bottom
cover and wafer carrier are removably retained together by the
bottom cover rim portions engaging and embracing lower rim portions
of the wafer carrier.
4. A plastic container according to claim 1 wherein a pair of
adjacent tab portions are affixed on the wafer carrier and the
bottom cover respectively.
5. A plastic container according to claim 1 wherein both of said
lower rim portions of the carrier and said bottom cover rim
portions lying substantially in adjacent planes and diverting out
of said planes in bypassing said indexing notches.
6. A plastic container for storing and shipping semiconductor
wafers, and interfacing with processing machines in indexed
relation, comprising
a substantially rigid wafer carrier comprising sidewalls with wafer
supporting offset portions and wafer separating ribs, the carrier
also comprising first and second end walls interconnecting the
sidewalls, the sidewalls and end walls comprising upper edge
portions defining a top opening of the carrier facilitating loading
and unloading of semiconductor wafers, the sidewalls and end walls
also defining lower edge portions defining a bottom opening of the
carrier providing access to wafers in the carrier, the lower edge
portions comprise a periphery of the bottom opening and also
comprise an enlarged lower rim on said sidewalls and end walls and
extends continuously around the periphery of the bottom opening of
the wafer carrier, said lower rim protruding outwardly of the
carrier and away from said bottom opening thereof each of said
sidewalls comprises a foot panel extending along the bottom opening
and defining said lower edge portion, the lower edge portion of the
foot panel comprising an indexing notch, said enlarged lower rim
bypassing and extending adjacent to the indexing notch.
Description
This invention relates to containers and packages for shipping
semiconductor wafers and similar objects.
BACKGROUND OF THE INVENTION
Semiconductor wafers are subjected to numerous steps in their
processing. The wafers are subjected to various process steps in
various machines and at various locations. The wafers must be
transported from place to place and stored over a period of time in
order to accommodate the necessary processing. Numerous types of
shipping devices have been previously known for wafer carriers and
in the past, the principal effort has been to protect the
semiconductor wafers against physical damage. Such shipping
containers and packages have been previously known as disclosed in
U.S. Pat. Nos. 4,248,346; 4,557,382; 5,253,755; and 5,273,159.
Those devices which utilize wafer carriers which are suitable for
handling the wafers during actual processing of the wafers have not
provided any degree of sealing to protect wafers against
contamination due to moisture, various atmospheric conditions and
particulates.
SUMMARY OF THE INVENTION
An object of the invention is to provide a shipping container for
safely storing large sized semiconductor wafers and to minimize
likelihood of contamination of the wafers with particulate,
moisture or other contaminating mediums.
A feature of the invention is a wafer carrier with an open top and
an open bottom and wafer separating ribs on the sidewalls, all of
the sidewalls and end walls being uniformly of full height and one
of the end walls having an external transverse indexing crossbar to
accommodate locating the carrier in processing equipment. The top
and bottom edges of the sidewalls and end walls substantially lie
in planes to facilitate application of top and bottom covers to the
carrier.
Another feature of the invention is the provision of cooperating
interlocking beaded edge or rim portions on the carrier and on the
sealing cover to fit together with a snap fit and produce a
substantial seal to minimize any migration of airborne particulate,
moisture and gases into and out of the carrier.
Still another feature provides that the sealing cover is molded of
a stiff but relatively flexible plastic which allows the cover to
be removed by flexing a corner portion of the cover to lift the
corner portion off the carrier, and then progressively lifting
other adjacent portions of the cover off the carrier. This flexing
of the cover simulates peeling the cover off the carrier.
A further feature is the provision of a lifting tab on one side of
the snap fit cover and a tab on an adjacent portion of the carrier
as to essentially require that the cover always be lifted at said
one side.
The cover, at the side opposite the tabs, relates to the adjacent
top edge portion of the carrier in a hinging relation and bears
downwardly against a tab portion on the carrier to lift the cover
off the carrier as the cover is tilted upward.
Still another feature of the invention is a package for shipping
semiconductor wafers wherein a multiplicity of shipping containers
contained semiconductor wafers are stacked onto cover trays which
carry the individual shipping containers in storage compartments of
cover trays which underlie and overlie a number of the shipping
containers which are supported on a cover tray. The shipping
containers are provided with outwardly projecting tabs adjacent the
top cover and the cover trays support the shipping containers by
engaging and supporting the tabs which effectively suspend the
container in the storage compartment. Another cover tray overlies
the shipping containers in the storage compartments and bear
downwardly on the edge portions of the cover to maintain the covers
on the wafer carriers to maintain the sealed condition within the
shipping containers.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view of a plastic shipping container.
FIG. 2 is a perspective view of the shipping container in exploded
condition to show the three principal parts; and having portions of
the wafer carrier broken away for clarity of detail.
FIG. 3 is a section view through the shipping container, taken on a
broken line as indicated at 3--3 in FIG. 1, and wherein the break
is taken at the center line indicated by dot dash lines in FIG.
3.
FIG. 4 is a section view taken approximately at 4--4 of FIG. 1 and
showing several semiconductor wafers being stored in the
container.
FIG. 5 is an enlarged detail section view taken approximately at
5--5 of FIG. 1.
FIG. 6 is an enlarged detail section view taken approximately at
6--6 of FIG. 1.
FIG. 7 is an enlarged detail elevation view showing the lower edge
portion of the sidewall of the carrier and the adjacent portions of
the bottom cover, in exploded condition.
FIG. 8 is an enlarged detail section view taken approximately at
8--8 of FIG. 1.
FIG. 9 is a perspective view illustrating a package for shipping a
multiplicity of the shipping containers illustrated in FIGS.
1-8.
FIG. 10 is a top plan view of the stack of cover trays illustrated
in FIG. 9.
FIG. 11 is a detail section view, broken away for clarity of detail
and taken approximately at 11--11 of FIG. 10.
FIG. 12 is a detail section view, partly broken away for clarity of
detail and taken approximately at 12--12 of FIG. 10.
FIG. 13 is an enlarged detail section view taken approximately at
13--13 of FIG. 12.
FIG. 14 is an enlarged detail section view taken approximately at
14--14 of FIG. 12.
DETAILED SPECIFICATION
The shipping container is indicated in general by numeral 15 and
comprises a wafer carrier 16, a top cover 17 and a bottom cover
18.
The wafer carrier 16 is preferably molded of a substantially rigid
and transparent plastic material, such as polycarbonate, although
the wafer carrier might be molded of other comparable or equivalent
plastics. The top cover 17 and bottom cover 18 are both molded of a
substantially stiff but resiliently and flexibly yieldable plastic
material, such as a thermoplastic elastomer known by its trademark
Hytrel.RTM., a registered trademark of DuPont. The Hytrel
thermoplastic elastomer, in all of its grades, are block
copolymers, consisting of a hard (crystalline) segment of
polybutylene terephthalate and a soft (amorphous) segment based on
long-chain polyether glycols. The particular material used in the
top and bottom covers 17 and 18 has a hardness, durometer D in the
range of 45 to 55 to 63, and the material is elastic and has a
sticky tack at the surface, providing for maximum grip and minimum
creep of material and a high abrasion resistance. In addition, the
stiff but resiliently yieldable material in the top and bottom
covers resists deterioration from many industrial chemicals, oils
and solvents.
The wafer carrier 16 comprises four encompassing walls specifically
identified as sidewalls 19 and 20 and end walls 21 and 22. The
sidewalls 19 and 20 and end walls 21 and 22 are molded integrally
of each other so that the plastic wafer carrier 15 is in one piece.
The upper edge portions 19.1, 20.1, 21.1 and 22.1 of the sidewalls
and end walls are in substantially linear relation to each other
with respect to each other, lying in a plane and defining the top
opening 23 of the carrier facilitating loading the wafers W into
the wafer carrier and unloading the wafers from the wafer
carrier.
The sidewalls 19 and 20 have a multiplicity of upright ribs or
teeth 24 and 25 formed integrally thereof and defining pockets or
slots 25.1 therebetween for receiving and retaining the
semiconductor wafers W in spaced relation with each other. The
transparent polycarbonate of the sidewalls 19, 20 facilitate
viewing the wafers to determine their presence and location. The
sidewalls 19 and 20 also have rounded offset portions 26 and 27
shaped to conform generally to the shape of the wafers W to be
carried therein. The offset portions have additional wafer
separating lugs 28 and 29 for maintaining the wafers W in spaced
relation to each other and in quiet relation with respect to each
other.
The sidewalls 19 and 20 also have depending and parallel foot
panels 30 and 31 defining the lower edge portions 32 and 33 of the
sidewalls 19 and 20, respectively.
End walls 21 and 22 are both substantially flat or planar and have
lower edge portions 34 and 35 which are arranged generally in the
same plane as the lower edge portions 32 and 33 of the sidewalls 19
and 20. The interconnected lower edge portions 32, 33, 34 and 35 of
the sidewalls and end walls cooperate to define the bottom opening
36 of the carrier between the foot panels 30 and 31 in order to
provide access to the wafers W at the bottom of the carrier 16.
The sidewalls 19 and 20 have outwardly protruding tabs 37 and 38
molded integrally of the upper edge portions 19.1 and 20.1 of the
sidewalls, and the tabs 37 are elongate and extend longitudinally
along the sidewalls, substantially midway between the ends of the
sidewalls, substantially as illustrated in FIG. 1. The sidewalls 19
and 20 also have lower tabs 39 and 40 protruding outwardly from the
lower edge portions 32 and 33 of the sidewalls and specifically
from the foot panels 30 and 31 thereof. The tabs 39 and 40 are
arranged as mirror images of each other, the tab 39 being
illustrated in FIG. 1 and tab 40 being illustrated in FIG. 4 in
dotted lines.
The upper and lower tabs 37-40 are particularly useful in manually
lifting and handling the carrier 16 and container 15, and the upper
tabs 37, 38 are also used to suspend the container 15 during
storage or shipment, see FIGS. 9-14. The tabs are also useful in
applying the cover 17, 18 to the carrier 16.
The upper edge portions 19.1, 20.1 of the sidewalls and the upper
edge portions 21.1, 22.1 of the end walls define enlarged and
outwardly flared upper rim portions 41, 42 on the sidewalls 19, 20
and rim portions 43, 44 on the end walls 21, 22, respectively. The
enlarged upper rim portions 41-44 connect with each other and
accordingly provide rim portions extending around the entire
periphery of the carrier 16, i.e. along both sidewalls and end
walls. The peripherally extending rim portions 41-44 lie
substantially in a plane.
The sidewalls 19 and 20 and the end walls 21 and 22 also define
enlarged and outwardly flaring lower rim portions 45, 46, 47 and
48, respectively, which join together and effectively provide lower
rim portions around the entire periphery of the carrier 16. The
lower rim portions lie substantially in a plane.
Each of the foot panels 30 and 31 has an indexing notch 49 formed
therein to cooperate with indexing ribs or media in a processing
machine for accurately locating the wafer carrier 16 in such a
processing machine. The two lower rim portions 45 and 46 on the
foot panels 30 and 31 of the sidewalls 19 and 20 diverge upwardly
as at 50 and pass over the indexing notch 49. The shape of the
enlarged lower rim portion 45 illustrated in FIG. 6 illustrates the
shape of all of the enlarged lower rim portions 45, 46, 47 and 48
with the exception of the portions 50 of the enlarged lower rim
portion 45, 46 which diverge out of the plane of the rim portions
and pass over the indexing notches 49.
It is to be particularly recognized that all portions of the end
walls 21 and 22 are of substantially uniform height, and of the
same height as the sidewalls 19 and 20. The end wall 22 has a pair
of widely spaced support bars 51 and 52 formed integrally thereof
and extending into close proximity with the upper and lower edge
portions 22.1 and 35, respectively, of the end wall 22. The support
bars 51 have coplanar outer edges 53 to lie on a plane surface of a
processing machine for the purpose of accurately locating the wafer
carrier and the wafers relative to other equipment in the
processing machine. The end wall 22 also has an indexing crossbar
54 formed integrally thereof, and is sometimes referred to as an
"H-bar", extending transversely of the support bars 51, 52. The
indexing crossbar 54 accurate locates the wafer carrier 16 in a
processing machine by cooperating with the locating mechanism
thereof. While the crossbar 54 is shown to extend entirely to the
support bars 51, 52, but may extend only partially across the end
wall 22 between the support bars. The crossbar 54 is also formed
integrally and in one piece with the end wall 22.
It is to be particularly noted that both end walls 21 and 22 have
the full height which is the same as the height of the sidewalls
19, 20; and the end walls 21 and 22, as well as the sidewalls, have
the enlarged upper and lower rim portions which effectively extend
around the entire periphery of the carrier 16. The end wall 22 in
particular has panel portions 55 and 56, which respectively extend
upwardly from the indexing crossbar 54 to the enlarged upper rim
portion 44, and downwardly from the indexing crossbar 54 to the
enlarged lower rim portion 48, respectively. Both of the panel
portions 55 and 56 fill the entire spaces between the support bars
51, 52, which are formed integrally of the end wall 22.
Both the top cover 17 and the bottom cover 18, when applied to the
upper and lower portions of the carrier to respectively close the
top opening 23 and bottom opening 36 thereof, establish a hermetic
sealing relations with respect to the carrier to essentially
prevent migration of air, moisture and contaminating particles
either into or out of the open interior 57 of the carrier wherein
the wafers W are stored. In addition, because both the top cover 17
and bottom cover 18 are formed or molded of a substantially stiff,
but resiliently flexibly yieldable plastic material, these top and
bottom covers 17, 18 may be flexed slightly during removal thereof
so as to essentially peel the covers off the carrier by initially
lifting one corner of the cover off the carrier and then
progressively disengaging the remainder of the cover from the
carrier.
The top cover 17 comprises a partially cylindrical panel or
retainer portion 58 having the curvature substantially the same as
the shape of the edges of the wafers W to be stored in the
container 15. In one successful example of the container, the
wafers may have a diameter of approximate eight inches (20.3 cm)
and the curvature of the panel 58 appropriately substantially
duplicates the curvature of the edge of panels of such size. The
container 15 is also suited to store 6 inch (15 cm), twelve inch
(30 cm) or larger wafers by making the container an appropriate
size. The partially cylindrical panel 58 has a convex inner surface
facing the open interior 57 of the wafer carrier; and the panel 58
also has a multiplicity of elongate spacer means or beads or ridges
60 extending longitudinally along the partially cylindrical inner
surface and protruding slightly toward the open interior 57 of the
carrier to engage the edges of the wafers W and maintain a spaced
relation between the edges of the wafers and the convex surface 59
of panel 58. As illustrated in FIG. 4, the elongate beads 60 extend
throughout the full length of the cover 17 and of the panel 58 so
as to overlie and engage all of the wafers that may be stored in
the container.
The top cover 17 also has substantially flat and planar side edge
portions 61, 62, 63, 64. It will be recognized that the side edge
portions 61, 62, adjacent the carrier sidewalls 19 and 20, provide
springiness in the cover, and are substantially wider than the end
edge portions 63, 64 which are adjacent the end walls 21, 22 of the
carrier. The side edge portions 61-64 lie directly on the upper
edge portions 19.1, 20.1, 21.1. and 22.1 of the carrier and
contribute to maintaining the hermetic seal between the carrier and
the top cover.
The top cover 17 also has a multiplicity of deformations or
stacking offsets 65 formed in the panel 58 to facilitate stacking
of the containers one upon another.
The top cover 17 also has enlarged top cover rim portions extending
around the entire periphery of the top cover and more specifically,
the top cover has inwardly protruding enlarged top cover rim
portions 66, 67 extending all along the side edge portions 61, 62
of the top cover; and has enlarged top cover rim portions 68, 69
extending all along the end edge portions 63, 64. All of the
enlarged top cover rim portions 66, 67, 68, 69 are interconnected
and formed integrally of each other and lie in a plane. When the
top cover 17 is applied onto the carrier 16, the rim portions 66-69
engage and embrace the rim portions 41-44 of the carrier 16 in
hermetic sealing relation. The rim portions 66-69 of the cover 17
and rim portions 41-44 of the carrier provide a snap fit for
securing the cover 17 onto the carrier 16. The interfitting rim
portions 66-69 on the cover and the rim portions 41-44 on the
carrier 16 provide the sole means by which the cover 17 is anchored
onto the carrier 16, i.e., there is no other latching devices for
holding the cover 17 onto the carrier 16.
Cover 17 also has a pair of tab portions 70, 71 which protrude
outwardly from the rim portion 67 and extend longitudinally along
the rim portion 67 and side edge portion 62 adjacent the ends of
the top cover to be in offset relation with respect to the adjacent
tab 38 on the carrier 16. The tabs 70, 71 are useful in completing
closing of the top cover 18 onto the carrier 16. In the final
stages of applying the top cover, the tabs 70, 71 may be manually
squeezed toward the tab 38 on the carrier to assure that
application of the bottom cover is completed, and that the snap fit
has been finished.
Although technicians using the container 16 may devise various
procedures of applying and removing the top cover 17, it has been
found to be successful to first place the top cover 17 upon the
upper edge portions of the side and end walls. The two corners of
the top cover may be pressed, initially, onto the rim portions of
the side and end walls using the palm or heel of the person's
hands. Then the side edge portions 61, 62 of the top cover are
progressively pressed onto the rim portions 41, 42 at the sidewalls
of the carrier, until the entire rim portions 66-69 of the cover
have achieved and completed the snap fit onto the adjacent rim
portions 41-44 of the carrier.
For removing the top cover 17, a corner portion, such as adjacent
rim portions 67 and 69, are lifted off the adjacent rim portions
42, 44 of the carrier, and the corner portion of the top cover is
flexed upwardly. The rim portions are progressively separated by
lifting on the top cover until the cover is free of all of the rim
portions 41-44 of the carrier.
The particular materials from which the carrier 16 and cover 17 are
formed are highly resistant to abrading and scuffing and
accordingly, the generation of particulate is minimized as the
cover is lifted off or applied onto the carrier.
The bottom cover 18 has side edge portions 72 and end edge portions
73 which respectively underlie the lower edge portions 32, 33 and
34, 35 of the carrier and engage the lower edge portions of the end
walls and sidewalls of the carrier to contribute materially to a
hermetic sealing relation between the bottom cover 18 and the
carrier 16. The bottom cover 18 has a central wafer supporting
portion 74 offset with respect to the edge portions 72, 73 as to
protrude upwardly into the bottom opening 36 of the carrier 16.
More specifically, the wafer supporting portions 74 comprises a
partially cylindrical panel 75 with a convex inner surface which
faces the interior 57 of the wafer carrier and the edges of the
wafers W confined therein. The curvature of panel 75 conforms to
the shape of the wafers W. The panel 75 also has a pair or
plurality of elongate wafer lifting means or beads or ridges 77
formed integrally thereof and protruding from the convex surface
inwardly of the interior 57 of the carrier 16 as to engage and
support the edges of the wafers W. The beads 77 actually lift the
wafers W out of engagement with the offset portions 26, 27 of the
sidewalls 19, 20 so that the wafers are free of the sidewalls and
are entirely supported upon one or both of the beads 77, regardless
of the location of the flat edge portions of the wafers. The
elongate beads 77 extend longitudinally along the partially
cylindrical panel 75 and extend substantially to the ends of the
bottom cover 18.
The bottom cover also has rim portions extending around the entire
periphery of the bottom cover and more specifically, the bottom
cover comprises enlarged rim portions 78, 79 extending along the
side edge portions 72 of the bottom cover and embracing the rim
portions 45, 46 of the sidewalls 19, 20 of the carrier. The bottom
cover also enlarged bottom cover rim portions 80, 81 extending
along the end edge portions 73 of the bottom cover and embracing
the enlarged rim portions 47, 48 of the end walls of the carrier
16. The rim portions 78, 79, 80 and 81 are all interconnected with
each other and lie substantially in a plane and embrace the rim
portions 45, 46, 47 and 48 of the wafer carrier in a snap fit and
in hermetic sealing relation to retain the bottom cover on the
wafer carrier. The rim portions 78-81 of the bottom cover and the
rim portions 45-48 of the wafer carrier comprise the sole means by
which the bottom cover is retained on the wafer carrier, i.e.,
there need be no supplemental latching means for holding the bottom
cover on the carrier.
The hermetic seal between the carrier 16 and the top and bottom
covers 17, 18 prevents movement of air, other gases, moisture and
particles into and out of the container 15, and prevents the
carrier from burping or sucking as atmospheric pressures
change.
The bottom cover 18 also has a pair of elongate tab portions 82, 83
extending longitudinally along one of the side edge portions 72 and
adjacent the rim portion 79 of the bottom cover. The tab portions
82, 83 lie adjacent, but in offset relation, with respect to the
adjacent tab 40 on the lower side edge portion of the wafer carrier
so as to facilitate a person simultaneously engaging and squeezing
both of the tab portions 83 and 40 and assuring that the snap fit
has been completed in applying the bottom cover onto the carrier.
Ordinarily the bottom cover 18 is applied to the carrier by laying
the bottom cover 18 on a support table, then the carrier 16 is
placed upon the bottom cover and pressed so as to secure the
carrier 16 and cover 18 together in a snap fit. If the wafers W are
already in the carrier, the wafers will be lifted by the bottom
cover 18 off the offset portions 26, 27 of the sidewalls 19,
20.
In removing the bottom cover 18 from the wafer carrier, one corner
portion of the bottom cover is flexed, as above described in
connection with the top cover, and the bottom cover 18 may thereby
be progressively disengaged from the enlarged lower rim portions
45-48 of the wafer carrier for removing the bottom cover. The rim
portions 78-81 of the bottom cover engage and embrace the rim
portions 45-48 of the wafer carrier and establish a hermetic
sealing relation between the bottom cover 18 and the wafer carrier
to prevent migration of air, moisture and particulate into or out
of the interior 57 of the wafer carrier. Whereas the bottom cover
rim portions 78-81 lie substantially in a plane, portions 78.1,
79.1 of the rim portions 78, 79 extending along the side edge
portions 72 of the bottom cover, are diverted out of the plane of
the remainder of the bottom cover rim portions to conform to the
shape of the portions 50 of the rim portions 45, 46 which diverge
out of the planes of the rim portions on the wafer carrier and pass
over the index notches 49 in the foot panels 30, 31 of the wafer
carrier.
The bottom cover 18 also has outwardly protruding lip portions 84
protruding outwardly all around the periphery of the bottom cover
except at the tabs 82, 83 to add strength to the bottom cover.
Similarly, the top cover 17 has outwardly protruding lip portions
85 protruding outwardly from the edge portions of the top cover all
the way around the periphery of the top cover except at the tabs
70, 71 to provide additional strength to the top cover.
The lip portions 85 which extends along the rim portion 66 and the
side edge portion, engages the tab 37 of carrier 16 as the top
cover is tilted upward during removal, and assists in lifting and
disengaging rim portion 66 from rim portion 41 of the carrier.
FIGS. 10-14 illustrate the shipping container 15 packaged in
clusters for shipment so as to deliver semiconductor wafers W for
processing. The package is indicated in general by numeral 84 and
comprises a multiplicity of cover trays 85 assembled in nesting and
stacked relation to each other. The cover trays 85 are molded of
foamed plastic and particularly, foamed polypropylene, providing
cushioning for the containers 15. Of course, other foamed plastics
may be substituted to provide the necessary cushioning for the
containers 15. The foamed plastic of the trays 85 is capable of
absorbing shock in view of the compressibility of the material and
the limited resilience thereof. Each of the cover trays has an
upper portion 86 and a lower portion 87.
Although FIG. 9 illustrates a stack of nine trays, i.e., eight
levels of containers 15, the package 84 may have lesser number for
stacked trays. Often only five trays are utilized in such a package
84.
The upper portion 86 of each of the trays 85 has a multiplicity of
open top storage compartments 88 arranged in rows and files, and in
the form illustrated, each cover tray has 16 storage compartments
formed therein. Each of the storage compartments 88 is shaped to
receive a single plastic shipping container therein. The
compartments 88 are shaped so that the sidewalls 89 thereof have
the same shape as the shape of the sidewalls 19 and 20 of the
container 15. Similarly, the compartments 88 of the cover trays are
shaped so that the end walls 90 thereof are substantially flat as
to conform substantially to the shape of the end walls 21, 22 of
the carrier 16. The bottom surface 91 of each of the compartments
88 is substantially flat to conform substantially to the flat shape
of the side and end edge portions 72, 73 of the bottom cover 18 of
each of the containers 15.
The upper portion 86 of each of the cover trays 85 also defines a
support shelf 92 adjacent each of the sidewalls 89 for supporting
the tab portions 37, 38 of the wafer carrier 16 of each of the
containers 15. The upper tabs 37, 38 of the wafer carrier are
thereby supported on the upper portion 86 of the cover tray; and
each of the containers 15 is thereby suspended from the support
shelves 92 in a compartment of the cover tray. As illustrated in
FIG. 14, the containers 16 are suspended from the tabs 37, 38
resting upon the support shelves 92 so that the bottom covers 18
are spaced slightly off the bottom surfaces 91 of the compartments
88. As a result, no pressure is applied through the bottom covers
onto the wafers contained in the containers 15.
The lower portions 87 of each of the cover trays 85 overlie the
upper portions 86 of the cover trays therebelow; and the lower
portions 87 of each of the cover trays has a bottom panel 93
forming the bottom surface 91 of the compartments 88, and the
bottom panels 93 also overlies the compartments of the trays
therebelow. The bottom panels 93 have lower surfaces shaped to
conform to the shape of the top covers 17 of the containers 15, and
as seen in Figure 11, the surfaces 93.1 are also substantially
partially cylindrical as are the panels 58 of the top covers 17.
The surfaces 93.1 if the bottom panels 93 are spaced from the top
covers 17 of the containers 15 so that no pressure is brought to
bear on the partially cylindrical panels 58 of the covers 17.
The lower portions 87 of the cover trays define elongate support
feet 94 bearing downwardly upon the side edge portions 61, 62 of
the covers 17, as particularly seen in FIG. 13. The support feet 94
are formed adjacent both sidewalls 88 of each compartment and bear
downwardly against both side edge portions 61, 62 of each cover 17,
and extend all along the length of the covers and of the side edge
portions 61, 62. The cover trays 85 thereby bear down on the side
edge portions 61, 62 of all of the containers 15 as to continuously
hold the covers tightly onto the wafer carriers 16 and maintain the
top covers 17 in hermetic sealing relation with the wafer carriers
16.
In order to provide for nesting of the cover trays together and
stacking of the trays one upon the other while maintaining the
trays in vertical alignment as illustrated in FIG. 9, the upper
portions 86 of the cover trays and the lower portions 87 of the
cover trays both have interfitting offsets 95 and 96. When the
cover trays are stacked one upon the other, the offsets 95 and 96
fit together and prevent any sideward movement of the trays,
thereby maintaining the trays in vertical alignment as illustrated
in FIGS. 9, 11 and 12.
After the trays have been filled with containers 15 in all of the
compartments, and the trays have been stacked one upon the other as
illustrated in FIG. 9, the entire column of trays is preferably
provided with a shrink wrapping 97 as to secure all of the trays
together. Such shrink wrapping is simply a wrapping of plastic film
which is subjected to heat and thereby shrunk to grip the trays
tightly.
The stack of trays or package 84 may be supported by its own pallet
98. The package 84 may be assembled with a number of other
identical packages 84 in a cluster and supported on a pallet 98.
The assembled packages 84 are then shrink wrapped for stability and
ease of handling.
It will be recognized that because the containers 15 are supported
from their tabs 37, 38 on the shelves 92, the cushioning effect of
the foamed polypropylene plastic material in the cover trays is
utilized for producing individual cushioning for each container. In
the event that the entire package 84 is subjected to some physical
shock, the transfer of the shock to the wafer carriers within the
containers 15 is minimal. Even though the bottom covers 18 of the
container may temporarily engage the bottom surfaces 91 of the
compartments 88, the wafer carriers are held in spaced relation to
the partially cylindrical panels 75 of the bottom cover by the
elongate beads or ridges 77, again providing additional cushioning
to prevent the wafers from being damaged within the containers 15.
The entire clusters of packages 84 as illustrated in FIG. 9 may
also be shrink wrapped together on the pallet 98. After the
containers have arrived at their destination, they may be cleaned
and reused.
The present invention may be embodied in other specific forms
without departing from the spirit or essential attributes thereof,
and it is therefore desired that the present embodiment be
considered in all respects as illustrative and not restrictive,
reference being made to the appended claims rather than to the
foregoing description to indicate the scope of the invention.
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